Minimum detectable effect size for main outcomes (accounting for sample
design and clustering)
Given our sample design and stratification of assignment, our power analysis without covariate control reveals a minimum detectable effect size of 5%, with power = 0.8 and alpha = 0.05, to distinguish groundwater use differences between treatment and control wells. However, with the inclusion of covariate control in the power analysis, specifically groundwater management district specific effects lagged well-level pumping, we find a minimum detectable effects size of 0.03, with power = 0.8 and alpha = 0.05. We use data on past well-level pumping to conduct the power analysis.